1c_csa2s(3NCARG)                  NCAR GRAPHICS                 c_csa2s(3NCARG)
2
3
4

NAME

6       c_csa2s  - cubic spline approximation, simple entry for two-dimensional
7       input, gridded output
8

FUNCTION PROTOTYPE

10       float *c_csa2s(int, float [], float [], float [], int [],
11                      int, int, float [], float [], int *);
12
13

SYNOPSIS

15       int c_csa2s(int n, float xi[], float yi[], float zi[], int knots[2],
16                   int no, int mo, float xo[], float yo[], int *ier);
17
18

DESCRIPTION

20       n           (integer,input) The number of input data points. It must be
21                   that  n  is  greater  than  3 and, depending on the size of
22                   knots below, n may have to be larger.
23
24       xi          (real, input) An array dimensioned for n containing  the  X
25                   coordinate values for the input function.
26
27       yi          (real,  input)  An array dimensioned for n containing the Y
28                   coordinate values for the input function.
29
30       zi          (real, input) An array containing the functional values  of
31                   the  input  function  --  zi[k]  is the functional value at
32                   (xi[k], yi[k]) for k=0,n-1.
33
34       knots       (integer, input) The number of knots to  be  used  in  each
35                   coordinate  direction  in  constructing  the  approximation
36                   spline.  knots[0] and knots[1] must  be  at  least  4.  The
37                   larger  the  value  for  knots, the closer the approximated
38                   curve will come to passing through the input function  val‐
39                   ues.
40
41       no          (integer,  input)  The  number of X coordinate values to be
42                   calculated for the output surface.
43
44       mo          (integer, input) The number of Y coordinate  values  to  be
45                   calculated for the output surface.
46
47       xo          (real,  input) An array dimensioned for no containing the X
48                   coordinates of the output grid.
49
50       yo          (real, output) An array dimensioned for mo containing the Y
51                   coordinates of the output grid.
52
53       ier         (pointer to integer, output) An error return value. If *ier
54                   is returned as 0, then no errors were detected. If *ier  is
55                   non-zero,  then  refer to the error list in the error table
56                   for details.
57

USAGE

59       c_csa2s is called to find an approximating  cubic  spline  surface  for
60       two-dimensional  input  data. If you want to weight the input data val‐
61       ues, calculate derivatives, or handle data sparse areas specially, then
62       you will need to use c_csa2xs.
63
64       c_csa2s returns a pointer to a linear array of data that is the approx‐
65       imated grid stored in row-major order. That is, if out is declared as
66
67         float *out;
68
69       and we set:
70
71         out = c_csa2s(n, x, y, z, knots, no, mo, xo, yo, &ier);
72
73       then out[i*mo+j] is the approximated function value at coordinate point
74       (xo[i],  yo[j])  for  0 <= i < no and 0 <= j < mo. The space for out is
75       allocated internal to c_csa2s and is no * mo floats in size.
76

ACCESS

78       To use c_csa2s, load the NCAR Graphics library ngmath.
79

SEE ALSO

81       csagrid, c_csa2xs, c_csa2ls, c_csa2lxs
82
83       Complete documentation for Csagrid is available at URL
84       http://ngwww.ucar.edu/ngdoc/ng/ngmath/csagrid/csahome.html
85

87       Copyright (C) 2000
88       University Corporation for Atmospheric Research
89
90       The use of this Software is governed by a License Agreement.
91
92
93
94UNIX                             January 1999                  c_csa2s(3NCARG)
Impressum